Both pharmacy and medicine have sought, since the beginning of antiquity, a delivery system for the controlled administration of a beneficial drug. The first written reference to a delivery system, a dosage form, is in the Eber Papyrus, written about 1552 B.C. The Eber Papyrus mentions dosage forms such as anal suppositories, vaginal pessaries, ointments, oral pill formulations, and other dosage preparations. About 2500 years passed without any advance in dosage form development, until the Arab physician Rhazes, 865-925 A.D., invented the coated pill. About a century later the Persian Avicenna, 980-1037 A.D., coated pills with gold or silver for increasing patient acceptability and for enhancing the effectiveness of the drug. Also, around this time, the first tablet was described in Arabian manuscripts written by Al-Zahrawi, 936-1009 A.D. The manuscripts described a tablet formed from the hollow impressions in two matched-facing tablet molds. Pharmacy and medicine waited about 800 years for the next innovation in dosage forms, when in 1883 Mothes invented the capsule for administering drug. The next quantum and profound leap in dosage forms came in 1972 with the invention of the osmotic delivery device by inventors Theeuwes and Higuchi. This unique osmotic delivery device is manufactured in one embodiment for oral use, and in this embodiment it embraces the appearance of a tablet with a drug delivery portal. It is the first oral dosage form that delivers throughout the entire gastrointestinal tract a known amount of drug per unit time at controlled rate of delivery. The oral osmotic device maintains its physical and chemical integrity during the prolonged period of time it transits the total length of the gastrointestinal tract.
The oral route is the most ancient route of drug administration, and it is the most convenient route for admitting a drug into the systemic circulation. The oral route can be used for administering drugs that are absorbed into systemic circulation from all regions of the gastrointestinal tract including the stomach, small intestine and the large intestine, and it can be used for administering drugs that are absorbed into systemic circulation from certain regions of the gastrointestinal tract, mainly the stomach and the small intestine. The presently available oral, osmotic device delivers drugs that are absorbed from all regions of the gastrointestinal tract. It will be appreciated by those versed in the oral dispensing art in view of this presentation, that a critical and urgent need exists for an osmotic device that can deliver drugs only to certain regions of the gastrointestinal tract. The need exists for an oral osmotic device that can deliver drug to certain regions of the gastrointestinal tract including the stomach and the small intestine for making the maximum amount of drug available for absorption in these drug-absorbing regions. The need exists also for an osmotic device that delivers drug in the region of drug absorption, and concomitantly substantially avoids drug delivery in other regions of the gastrointestinal tract, including the large intestine where the drug may not be absorbed into the systemic circulation.